Cryptosporidium parvum: oocyst excretion and viability patterns in experimentally infected lambs

Acute phase response in organic lambs associated with colostrum serum amyloid A, weight gain, and Cryptosporidium and Giardia infections

In neonatal period, lamb's immune system goes through rapid adaptation to the extra-uterine environment. Success of this process can influence the animal's future performance and, thus, the quantitative assessment of it would greatly benefit sheep producers. The current study was conducted to investigate the acute phase response (APR) (measured through serum amyloid A (SAA), haptoglobin (Hp) and albumin (ALB)) in relation to later life growth (measured at 122 days of age), and naturally occurring Cryptosporidium and Giardia infections in neonatal lambs grown in organic farm. Serum (n = 692) and faecal (n = 141) samples were collected from 269 lambs in their first 3 weeks of life. The ewes' colostrum (n = 181) SAA concentrations were positively associated with the lambs' serum SAA and Hp concentrations at 2 to 4 days of age. Hp and ALB concentrations at the second week of age were positively associated with the growth rate at 122 days of age. Lamb serum globulin (GLOB) concentrations and Cryptosporidium-positive faecal samples were negatively associated at the second and third weeks of life. These findings suggest the importance of interactions between the immune system and environmental factors at the second week of the lambs' lives and its association with future performance.

Cryptosporidiosis outbreak in visitors of a UK industry-compliant petting farm caused by a rare Cryptosporidium parvum subtype: a case-control study

A case-control study was conducted to investigate an outbreak of 46 cases of cryptosporidiosis in visitors to a petting farm in England. Details of exposures on the farm were collected for 38 cases and 39 controls, recruited through snowball sampling. Multivariable logistic regression identified that cases were 5·5 times more likely than controls to have eaten without washing their hands [95% confidence interval (CI) 1·51–19·9, P = 0·01] and 10 times less likely to report being informed of risk of infection on arrival (odds ratio 0·10, 95% CI 0·01–0·71, P = 0·02). An uncommon Cryptosporidium parvum gp60 subtype (IIaA19G1R1) was identified in a lamb faecal sample and all subtyped cases (n = 22). We conclude that lack of verbal advice and non-compliance with hand washing are significantly associated with a risk of cryptosporidiosis on open farms. These findings highlight the public health importance of effectively communicating risk to petting farm visitors in order to prevent future outbreaks of zoonotic infections.

Investigating source water Cryptosporidium concentration, species and infectivity rates during rainfall-runoff in a multi-use catchment

Protozoan pathogens present a significant human health concern, and prevention of contamination into potable networks remains a key focus for drinking water providers. Here, we monitored the change in Cryptosporidium concentration in source water during high flow events in a multi-use catchment. Furthermore, we investigated the diversity of Cryptosporidium species/genotypes present in the source water, and delivered an oocyst infectivity fraction. There was a positive and significant correlation between Cryptosporidium concentration and flow (ρ = 0.756) and turbidity (ρ = 0.631) for all rainfall-runoff events, despite variable source water pathogen concentrations. Cell culture assays measured oocyst infectivity and suggested an overall source water infectious fraction of 3.1%. No infectious Cryptosporidium parvum or Cryptosporidium hominis were detected, although molecular testing detected C. parvum in 7% of the samples analysed using PCR-based molecular techniques. Twelve Cryptosporidium species/genotypes were identified using molecular techniques, and were reflective of the host animals typically found in remnant vegetation and agricultural areas. The inclusion of molecular approaches to identify Cryptosporidium species and genotypes highlighted the diversity of pathogens in water, which originated from various sources across the catchment. We suggest this mixing of runoff water from a range of landuses containing diverse Cryptosporidium hosts is a key explanation for the often-cited difficulty forming strong pathogen-indicator relationships.

Isolation and amplification of mRNA within a simple microfluidic lab on a chip

The major modules for realizing molecular biological assays in a micro-total analysis system (μTAS) were developed for the detection of pathogenic organisms. The specific focus was the isolation and amplification of eukaryotic mRNA within a simple, single-channel device for very low RNA concentrations that could then be integrated with detection modules. The hsp70 mRNA from Cryptosporidium parvum was used as a model analyte. Important points of study were surface chemistries within poly(methyl methacrylate) (PMMA) microfluidic channels that enabled specific and sensitive mRNA isolation and amplification reactions for very low mRNA concentrations. Optimal conditions were achieved when the channel surface was carboxylated via UV/ozone treatment followed by the immobilization of polyamidoamine (PAMAM) dendrimers on the surface, thus increasing the immobilization efficiency of the thymidine oligonucleotide, oligo(dT)25, and providing a reliable surface for the amplification reaction, importantly, without the need for blocking agents. Additional chemical modifications of the remaining active surface groups were studied to avoid nonspecific capturing of nucleic acids and hindering of the mRNA amplification at low RNA concentrations. Amplification of the mRNA was accomplished using nucleic acid sequence-based amplification (NASBA), an isothermal, primer-dependent technique. Positive controls consisting of previously generated NASBA amplicons could be diluted 10(15) fold and still result in successful on-chip reamplification. Finally, the successful isolation and amplification of mRNA from as few as 30 C. parvum oocysts was demonstrated directly on-chip and compared to benchtop devices. This is the first proof of successful mRNA isolation and NASBA-based amplification of mRNA within a simple microfluidic device in relevant analytical volumes.

Individual subject meta-analysis of parameters for Cryptosporidium parvum shedding and diarrhoea in animal experimental models

Cryptosporidium is a zoonotic protozoan parasite with public health importance worldwide. The objectives of this study were to (1) conduct a meta-analysis of published literature for oocyst shedding and diarrhoea outcomes, and (2) develop recommendations for standardization of experimental dose-response studies. Results showed that for the outcome of oocyst shedding in faeces, the covariates 'experimental species', 'immunosuppression', 'oocyst dose' and 'oocyst dose' × 'age' were all significant (P≤0.05). This study suggests that exposing mice, piglets, or ruminants, and using immunosuppressed experimental hosts, is more likely to result in oocyst shedding. For the outcome of diarrhoea in experimentally infected animal species, the key covariates 'experimental species', 'age' and 'immunosuppression' were significant (P≤0.2). Therefore, based on the results of this meta-analysis, these variables should be carefully reported and considered when designing experimental dose-response studies. Additionally, detection of possible publication bias highlights the need to publish additional studies that convey statistically non-significant as well as significant results in the future.

Molecular characterization of Cryptosporidium in Brazilian sheep

Feces were collected from 125 sheep between January and December 2007, on ten farms in the State of Rio de Janeiro, Brazil, and examined for the presence of Cryptosporidium. Ninety samples were collected from lambs 2 to 6 months of age, and 35 were from sheep over 12 months of age. All samples were subjected to molecular analysis by polymerase chain reaction (nested PCR) in two steps of the SSU rRNA. Two samples (1.6%) from the lambs were positive, and after sequencing were identified as Cryptosporidium ubiquitum. This species has been reported worldwide and it is considered a zoonotic pathogen since it has been found and in several animal species and humans. However, because of the low frequency of C. ubiquitum found, the risk for public health in this region may not be high.

Over-expression and localization of a host protein on the membrane of Cryptosporidium parvum infected epithelial cells

The genus Cryptosporidium includes several species of intestinal protozoan parasites which multiply in intestinal epithelial cells. The impact of this infection on the transcriptome of cultured host cells was investigated using DNA microarray hybridizations. The expression of 14 genes found to be consistently up- or down-regulated in infected cell monolayers was validated with RT PCR. Using immunofluorescence we examined the expression of Protease Activated Receptor-2, which is encoded by one of the up-regulated genes. In infected cells this receptor localized to the host cell membrane which covers the intracellular trophozoites and meronts. This observation indicates that the composition of the host cell membrane is affected by the developing trophozoite, a phenomenon which has not been described previously.

Cryptosporidium: detection in water and food

Water and food are major environmental transmission routes for Cryptosporidium, but our ability to identify the spectrum of oocyst contributions in current performance-based methods is limited. Determining risks in water and foodstuffs, and the importance of zoonotic transmission, requires the use of molecular methods, which add value to performance-based morphologic methods. Multi-locus approaches increase the accuracy of identification, as many signatures detected in water originate from species/genotypes that are not infectious to humans. Method optimisation is necessary for detecting small numbers of oocysts in environmental samples consistently, and further work is required to (i) optimise IMS recovery efficiency, (ii) quality assure performance-based methods, (iii) maximise DNA extraction and purification, (iv) adopt standardised and validated loci and primers, (v) determine the species and subspecies range in samples containing mixtures, and standardising storage and transport matrices for validating genetic loci, primer sets and DNA sequences.

Immunoenzymatic analysis and genetic detection of Cryptosporidium parvum in lambs from Italy

Cryptosporidiosis is a worldwide-diffused protozoan disease causing important economic losses to animal husbandry and livestock production. Additionally, several species/genotypes of Cryptosporidium have a relevant zoonotic potential and ruminants may be important sources of infection for human beings. Nonetheless, in Europe, little is known of the presence of Cryptosporidium in sheep nor on the species/genotypes involved. To obtain information on the occurrence of cryptosporidiosis in lambs and the potential zoonotic role of the Cryptosporidium isolates, one hundred and forty-nine faecal samples individually collected from lambs in central Italy have been examined for the presence of Cryptosporidium. All faecal specimens were processed with a commercial ELISA kit immunoassay and all ELISA-positive samples were further analyzed genetically. Twenty-six ELISA-positive samples scored positive at the PCR and the sequences obtained displayed 100% identity with the zoonotic Cryptosporidum parvum. This work suggests for the first time that lambs in Italy may shed C. parvum, thus representing a potential public health hazard.

Cryptosporidium genotypes and subtypes in lambs and goat kids in Spain

To provide information on the transmission dynamics of cryptosporidial infections in domestic small ruminants and the potential role of sheep and goats as a source for human cryptosporidiosis, Cryptosporidium-positive isolates from 137 diarrheic lambs and 17 goat kids younger than 21 days of age were examined by using genotyping and subtyping techniques. Fecal specimens were collected between 2004 and 2006 from 71 sheep and 7 goat farms distributed throughout Aragón (northeastern Spain). Cryptosporidium parvum was the only species identified by restriction analyses of PCR products from small-subunit rRNA genes from all 154 microscopy-positive isolates and the sequencing of a subset of 50 isolates. Sequence analyses of the glycoprotein (GP60) gene revealed extensive genetic diversity within the C. parvum strains in a limited geographical area, in which the isolates from lambs exhibited 11 subtypes in two subtype families (IId and IIa) and those from goat kids displayed four subtypes within the family IId. Most isolates (98%) belonged to the subtype family IId, whereas only three isolates belonged to the most widely distributed family, IIa. Three of the four most prevalent subtypes (IIdA17G1a, IIdA19G1, and IIdA18G1) were previously identified in humans, and five subtypes (IIdA14G1, IIdA15G1, IIdA24G1, IIdA25G1, and IIdA26G1) were novel subtypes. All IId subtypes were identical to each other in the nonrepeat region, except for subtypes IIdA17G1b and IIdA22G1, which differed by a single nucleotide polymorphism downstream of the trinucleotide repeats. These findings suggest that lambs and goat kids are an important reservoir of the zoonotic C. parvum subtype family IId for humans.

Estimating potential environmental loadings of Cryptosporidium spp. and Campylobacter spp. from livestock in the Grand River Watershed, Ontario, Canada

Exposure to waterborne pathogens in recreational or drinking water is a serious public health concern. Thus, it is important to determine the sources of pathogens in a watershed and to quantify their environmental loadings. The natural variability of potentially pathogenic microorganisms in the environment from anthropogenic, natural, and livestock sources is large and has been difficult to quantify. A first step in characterizing the risk of nonpoint source contamination from pathogens of livestock origin is to determine the potential environmental loading based on animal prevalence and fecal shedding intensity. This study developed a probabilistic model for estimating the production of Cryptosporidium spp. and Campylobacter spp. from livestock sources within a watershed. Probability density functions representing daily pathogen production rates from livestock were simulated for the Grand River Watershed in southwestern Ontario. The prevalence of pathogenic microorganisms in animals was modeled as a mixture of beta-distributions with parameters drawn from published studies. Similarly, gamma-distributions were generated to describe animal pathogen shedding intensity. Results demonstrate that although cattle are responsible for the largest amount of manure produced, other domesticated farm animals contribute large numbers of the two pathogenic microorganisms studied. Daily pathogen production rates are highly sensitive to the parameters of the gamma-distributions, illustrating the need for reliable data on animal shedding intensity. The methodology may be used for identifying source terms for pathogen fate and transport modeling and for defining and targeting regions that are most vulnerable to water contamination from pathogenic sources.

Susceptibility of five strains of Cryptosporidium parvum oocysts to UV light

Previous evaluations of the effect of ultraviolet (UV) light on Cryptosporidium parvum oocysts have been limited to a single strain—the Iowa strain. This study investigated the response of five strains of C. parvum to UV. A collimated beam apparatus was used to apply controlled doses of monochromatic (254 nm) UV to oocysts of the Iowa, Moredun, Texas A&M, Maine, and Glasgow strains. Irradiation was measured using a calibrated radiometer and sensor. Inactivation was quantified through animal infectivity by inoculation of cohorts of CD‐1 neonatal mice with UV‐treated and untreated control oocysts of each strain followed by examination of intestinal sections for infection using hemotoxylin and eosin staining. A UV light dose of 10 mJ/cm² achieved at least 4‐log₁₀ inactivation of all strains evaluated. All five strains of C. parvum were shown to be highly susceptible to low levels of UV light.

Long-term study of Cryptosporidium prevalence on a lowland farm in the United Kingdom

A longitudinal sample survey testing for Cryptosporidium in livestock and small wild mammals conducted over 6 years (1992-1997) on a lowland farm in Warwickshire, England, has shown the parasite to be endemic and persistently present in all mammalian categories. Faecal samples were taken throughout the year and oocysts concentrated by a formal ether sedimentation method for detection by immunofluorescence staining using a commercially available genus specific monoclonal antibody. Cryptosporidium parvum was identified by morphology and measurement of modified Ziehl-Neelsen stained oocysts. C. muris was rarely found in wild mammals and C. andersoni oocysts were never detected in livestock. Faecal samples from 3721 individuals gave cumulative 6-year prevalences for C. parvum as follows: bull beef, 3.6%; dairy cows, 3.5%; ewes, 6.4%; horses, 8.9%; calves (home bred), 52%; calves (bought-in) 23.2%; lambs, 12.9%; small wild mammals (rodents) living in and around farm buildings, 32.8%; small wild mammals (mainly rodents) living in areas of pasture, 29.9%. Animal categories with the highest prevalences also shed the highest average oocyst numbers per gram of faeces (ranging from 1.4 x 10(3) for bull beef to 1.1 x 10(5) for calves). Analysis of annual and seasonal data for each animal category revealed that patterns of infection were variable and sporadic; this means that short-term sampling was never likely to provide a true or representative picture. Seasonally combined data for adult livestock, young livestock and small wild mammals showed all three categories tended to have the highest Cryptosporidium prevalences in the autumn. Calves were separated from their dams within 24h of birth and yet showed high prevalence of infection in most years despite the low prevalence for the dairy herd. It is possible the coincidence of high autumn prevalence in mice with the main period for the rearing of calves contributed to the infection of the latter. The farming estate was used to teach students of agriculture and took pride in good land management and husbandry practices that produced well fed and healthy livestock. The data from this estate may represent, therefore, the baseline, the lowest possible levels to be expected, for Cryptosporidium infection and oocyst production on a lowland farm in the United Kingdom.

Prevalence of Cryptosporidium in sheep and goats bred on five farms in west-central region of Poland

Faecal specimens were taken from 205 sheep and goats housed in five different localities in the west-central part of Poland. All faecal specimens were examined for Cryptosporidium by using microscopy screening of smears stained by modified Ziehl-Neelsen technique and commercial enzyme immunoassay. PCR technique using genus specific primers was additionally applied in the surveys of 10 faecal specimens collected from lambs. C. parvum infection was identified in 16 of 159 sheep (10.1%). Lambs were more often infected than adult sheep, and the intensity of infection was higher in lambs than in sheep, as a rule. Both lambs and sheep examined in the study were asymptomatically infected with Cryptosporidium. Both microscopy and enzyme immunoassay methods gave one false negative result. The examination of 10 faecal samples revealed 100% agreement among the results obtained by microscopic, immunologic and molecular methods. None of the goats raised on three farms were infected with Cryptosporidium.

Inter-laboratory comparison of the CD-1 neonatal mouse logistic dose-response model for Cryptosporidium parvum oocysts

cryptosporidium parvum oocyst viability can be determined by vital dyes, in vitro excystation, and cell culture; however, neonatal mouse infectivity assays are the reference method. Unfortunately, there have been few efforts to standardize methods for infectivity assays thus casting a veil of uncertainty over the significance and comparability of results. In order to address this issue, two laboratories proficient in measuring oocyst infectivity conducted independent dose titration studies with neonatal CD-1 mice using standardized protocols and a well-characterized isolate of Cryptosporidium parvum. The resulting independent logistic dose-response models derived by regression analysis were compared with each other and with a published model. The comparisons showed these dose-response functions to be reproducible under standardized conditions. It is important to standardize mouse strain, age of mice at inoculation and necropsy, oocyst isolate, and age of oocysts. However, other factors, including methods used to detect infectivity and to count oocyst doses, appear less critical. Adopting a standardized assay for oocyst infectivity will provide both a basis for comparing data from various oocyst disinfection studies and a suitable platform for evaluating new or existing in vitro viability surrogates such as excystation, vital dyes or cell culture.

Role of Cryptosporidium parvum as a pathogen in neonatal diarrhoea complex in suckling and dairy calves in France

This study was carried out to find the importance of Cryptosporidium parvum in diarrhoea of neonatal calves in two types of breeding - suckling and dairy calves - in France. Different agents causing neonatal diarrhoea, E. coli, rotavirus, coronavirus, Salmonella and Cryptosporidium were systematically researched in faeces. 1. Suckling calves: In 40 livestock farms selected for diarrhoea, 311 calves 4 to 10 days old which had diarrhoea for less than 24h or no diarrhoea, were included in the study. A prophylaxis of neonatal diarrhoea had been carried out in 21 of the 40 livestock farms. On D0 (inclusion day), the mean age was 6 days, 82% presented a good initial general condition and 76.2% had a good appetite; 48.6% were diarrhoeic but 91.3% presented no sign of dehydration. Only 6.1% were infected by E. coli K99, 14.3% by rotavirus, 6.8% by coronavirus, 0.3% by Salmonella but 50% excreted C. parvum oocysts. This later percentage increases up to 84% and 86% by D3 and D7, respectively . We note that 16% of the 4-day-old calves on D0 are excreting oocysts and this percentage increases as a function of the age of the calf on D0 to reach 90% to 95% by the age of 8 days. 10 out of 12 dead calves excreted C. parvum oocysts. From D0 to D14 the other pathogen agents show a relative or a decreasing stability. 2. Dairy calves: 382 calves which had diarrhoea for less than 24 h or no diarrhoea, aged 8 to 15 days coming from six industrial livestock farms were included in the study. On D0, 99% of the calves presented a good initial general condition, 99.7% had a good appetite and no calf was dehydrated. At this date (D0), 16.8% of the calves excreted cryptosporidia. This percentage increases up to 23% and 51.8% on D3 and D8, respectively, then decreases to 31.9% on D14. The pressure of the other pathogenicagents remains relatively stable, excepted for rotavirus on D7 (from 9.9% on D0 to 27.2% on D7, then 12.6% on D14) which does not explain the concomitantpeak in diarrhoea because the infection by rotavirus on D7 is more frequent in non-diarrhoeic calves than in diarrhoeic calves. Our results show that Cryptosporidium prevalence is higher in suckling than in dairy calves and C. parvum constitutes actually in both cases the major aetiological agent of neonatal diarrhoea.

A review of the importance of cryptosporidiosis in farm animals

Cryptosporidium species are coccidian parasites with a large capacity to reproduce and to disseminate. Several species are known to infect farm animals, although the economic importance of cryptosporidiosis is highly host species dependent. This paper reviews the impact of cryptosporidial infections in livestock and poultry. For different farm animals, the Cryptosporidium spp. that occur, as well as their clinical and pathological features, and their interactions with other pathogens, are described. In addition, data concerning the prevalence, the transmission and the epidemiology of the disease are mentioned and a description of the economic losses associated with cryptosporidiosis in each of the hosts is given. Cryptosporidiosis seems to be mainly a problem in neonatal ruminants. Cryptosporidium parvum is considered to be an important agent in the aetiology of the neonatal diarrhoea syndrome of calves, lambs and goat kids, causing considerable direct and indirect economic losses. Avian cryptosporidiosis is an emerging health problem in poultry, associated with respiratory disease in chickens and other Galliformes, and with intestinal disease in turkeys and quails. Because of limited availability of effective drugs, the control of cryptosporidiosis relies mainly on hygienic measures and good management.

Role of adult sheep in transmission of infection by Cryptosporidium parvum to lambs: confirmation of periparturient rise

In sheep farms, oocyst shedding by asymptomatic adult carriers is one of the mechanisms which may explain maintenance of infections by Cryptosporidium parvum between lambing periods. The objective of this work was to investigate this hypothesis and the existence of a periparturient rise in oocyst shedding. Fourteen pregnant sheep were randomly selected from two farms with a history of neonatal diarrhoea caused by C. parvum and samples were collected from the 6th week before birth until 2 weeks after birth. Faecal samples were filtered, concentrated and examined for oocysts using an indirect immunofluorescence assay. The kinetics of anti-C. parvum antibodies (IgG and IgA) were studied using an indirect enzyme-linked immunosorbent assay. All except one animal excreted C. parrum oocysts at some time during the experimental period. The percentage of animals passing oocysts increased in the first week post-partum (farm 1) and in the first week before birth (farm 2). The numbers of oocysts excreted ranged from 20-440 oocysts g(-1) of faeces. In contrast, no significant changes in the anti-C. parvum immunoglobulin levels were observed over the sampling period. Finally, a high percentage of lambs (71%) born to these ewes acquired infection in the first 2 weeks of life.